Thermostat cycling

Eric_79

Hi guys, newbee here. 

I have a US Boiler X-C100, propane fired, for radiant in floor heat that I installed myself and have some questions/issues/concerns. At the beginning of the season I fired it up and all was well. Then after about a month the main control board went out. Luckily it is under warranty. So installed a new one and changed my set point temp from default of 180 to 125 degrees and set the short cycle timer to 10 minutes due to it was kicking on for only a few minutes then shutting down. I feel this constant cycling killed the board(just my theory). My concern now is the thermostat, an Aube Th135, differential temp is only 1 degree and non adjustable. It does have a switch for 15 minute or 20 minute cycling but I want less. My house is new (just finished building it in June) and does not loose hardly any heat. I have experimented different ways of running it. If I get up at my usual time of 6:30 am and turn it up from 65 to 69 and let it run to the temp it shuts off at, it will stay warm all day (outside temp is 28) and never run. If I leave it at 66 the differential is so sensitive it is trying to kick on every 5-10 minutes. I know for a fact there is no physical way the temp warms up that fast from the water in the floor. I feel it should run at least 15 minutes or so. I would rather have a 5 degree differential. 

 Will once a day be ok and efficient?

 If so, besides manually changing it, how can I better manage the cycle time?

I cannot find a once a day thermostat. I ordered a Honeywell TH5110D1022 which has a 1 cycle per hour setting. Hoping that works a little better.

Hope I gave enough info and sorry for the long post. Just getting frustrated. 

Thanks 
Eric

Big Ed_4

Radiant floor takes along time to heat up and cool down . A thermostat is used for ajusting ambient temperature and the cycle is used not to over ride the set point . A floor sensor is better suited for radiant heat . Mass heats mass is how radiant heat works . You want to control temperature of the floor...

With your board , did you check the voltage of the line to the boiler ? It could be to high or low ?

Jamie Hall

Don't try to run setbacks with a radiant floor. It annoys the boiler. With a radiant floor ideally what is wanted is constant circulation, but at just the temperature which keeps the floor warm enough to keep the space warm. This is best accomplished with an outdoor temperature sensor driving a mixing valve which controls the floor circulation temperature, while the boiler is on a separate primary loop and kicks in just enough hot water to keep the system running at the right temperature.

A space thermostat can be used to fine tune the floor circulating water temperature, if desired -- and the simpler the better. Programmable is quite unnecessary.

Eric_79

Big Ed, I have two wire from the thermostat to a Taco zvc403 valve controller. From the valve controller to the boiler is two wire. The voltage checks out for the specs in the manual.
Im just nervous of the boiler kicking on and off and the floor never getting close to warm due to just the movement of the air tripping the thermostat. 

Jamie, I don't have a circulation pump. I have a boiler pump and a system pump that only come on when there is call for heat. Once the temp is reached they shut off. 

Here is a picture of the system

Thanks guys
Eric